The invention relates to analyzing images.
Many people have had the experience of purchasing a product that is expected to include items or attributes in a predetermined pattern, and of finding that the article's usefulness is diminished by a defect relating to the pattern. If the product is meant to be a component in another product, the pattern-related defect may ruin the second product.
For this reason, products incorporating such predetermined patterns may be inspected for the compliance of the pattern with some standard. Examples include ball grid array devices, micro ball grid arrays, flip chips, and chip-scale packages (together called "BGAs"). BGAs share a common feature in that the contacts on the device are metallic balls that are mounted on one side of the device for forming electrical connections between the package's integrated circuit and a printed circuit board.
To work properly, the balls of BGAs should be properly located to connect to the pads on the circuit board. The balls also should be properly formed (i.e., should have a spherical shape and neither too much nor too little solder, to allow an acceptable electrical connection). The balls also should not be connected by extraneous solder or other material in the spaces between the balls. If these conditions are not met, the BGA may fail to make proper electrical connections or physical durable bonds.
Unlike traditional leaded devices that have contacts exposed on perimeters where some types of defects (e.g., solder bridges or missing solder) can be detected even after soldering, BGAs are harder to inspect after mounting on a circuit board. BGAs therefore are inspected before mounting, either in fully-assembled form or by inspection of ball arrays that are about to be attached to the packages of integrated circuits.
Similar inspections are done on other types of products, e.g., pill blister packs and candy sampler boxes.